46 



OSWALD SCHREINER AND J. J. SKINNER 



The exact chemical constitution of the nucleic acids is not known, 

 but these derivatives of it are well identified. There are prob- 

 ably many nucleic acids, depending upon which of these and other 

 bases enter into the molecule. 



EXPERIMENTAL METHOD 



In studying the effect of nucleic acid on crops, wheat seedlings 

 were grown in aqueous culture solutions containing the ordinary 

 fertilizer salts, calcium acid phosphate, sodium nitrate, and potas- 

 sium sulphate. Some of the cultures contained calcium acid 

 phosphate only, some sodium nitrate only, and some potassium 

 sulphate only. Other solutions were composed of mixtures of 

 two salts, sodium nitrate and calcium acid phosphate, sodium 

 nitrate and potassium sulphate, and calcium acid phosphate and 

 potassium sulphate. Still other solutions had all three constitu- 

 ents in various proportions. The concentration of all the solu- 

 tions was 80 parts per million of the fertilizer ingredients, P2O5, 

 NH3 and K2O. In cultures containing only one fertilizer salt, 

 for instance calcium acid phosphate, the concentration was 80 

 parts per million of P2O6. If two salts were present, for instance, 

 calcium acid phosphate and sodium nitrate, the concentra- 

 tion was 80 parts per million of P2O5 + NH3. If all three 

 salts were present the concentration was 80 parts per million of 

 P2O6 + NH3 + K2O. The ratios of these constituents varied 

 in 10 per cent stages. In all, there were 66 different cultures of 

 nutrient solutions. The details in preparing the solutions as 

 well as the principles involved in the scheme of experimentation 

 have been given in an earlier paper.'* 



Two sets of cultures were prepared; to one set were added 

 merely the nutrient salts, to a similar set 100 parts per million 

 of nucleic acid in each culture in addition to the nutrient salts. 

 The culture solutions were contained in wide-mouthed bottles, 

 holding 250 cc, and 10 wheat seedlings grown in each culture. 



Schreiner, O. and Skinner, J. J., Ratio of Phosphate, Nitrate, and Potassium 

 on Absorption and Growth, Bot. Gaz., 50: 1. 1910. 



